1. Field of the Invention
The present invention relates to a facsimile machine capable of receiving information service data called caller-ID inputted over a telephone circuit from a switchboard during a silent interval between a first ring signal and a second ring signal.
2. Description of the Related Art
There has been known a service provided by switchboards called caller-ID information service. A caller-ID is inputted over a telephone from a switchboard to a terminal circuit during a silent interval between a first ring signal and a second ring signal. The caller-ID includes various data including, depending on the country and the switchboard service, the date, the telephone number of the caller, the telephone number of the ring recipient, the type of ring, the caller's name, and the condition of the network system.
U.S. Pat. No. 4,582,956 describes a facsimile machine capable of receiving caller-ID data. In order to receive the caller-ID data, the modulation format of the modem must match that of the caller-ID data. The modulation format of the caller-ID data is FSK (frequency-shift keying). To match the modulation formats, the modem detects a single frequency signal added directly in front of the caller-ID data. In this way, detection of the single frequency signal acts as a trigger to start reception of the caller-ID data.